Molybdenum films such as these can be embedded in a gas-tight manner in quartz glass vessels, and are therefore used as a component of electrical supplies for light sources which are surrounded in a gas-tight manner by lamp vessels composed of quartz glass. This use of molybdenum films is described, for example, in German patent specification DE 573 448 for molybdenum films with a thickness of less than 20 micrometers, and for example in British patent specification GB 474 982 for thicker molybdenum films. In the following text and for the purposes of the invention described in the following text, the expression molybdenum film means metal films based on molybdenum, which are composed substantially of molybdenum. This means that the expression molybdenum film covers metal films which are composed of molybdenum or of molybdenum provided with additives and/or dopants, wherein the proportion by weight of the additives or dopants is considerably less than the proportion by weight of molybdenum in the metal film. By way of example, the expression molybdenum film also includes a metal film which is composed of molybdenum to which approximately 1 percent by weight of yttrium oxide or yttrium-cerium mixed oxide has been added.
Patent specification U.S. Pat. No. 4,587,454 discloses a method for production of a molybdenum film for lamp construction, according to which the surface of the molybdenum film is roughened by sandblasting in order in this way to prevent discontinuities or cracks in the quartz glass of the lamp vessel surrounding the molybdenum film.
Laid-open specification EP 1 156 505 A1 describes a molybdenum film for use as a component of electrical bushings through lamp vessels, wherein the molybdenum film has essentially non-cohesive, insular areas of substance agglomerates on 5 to 60 percent of its surface area with a surface structure which is different from the raw film and/or material compositions composed of molybdenum or of its alloys, of titanium, of silicon or of an oxide, a mixed oxide and/or of an oxidic compound with a vapor pressure of in each case less than 10 millibars at 2000° C.
Patent specification U.S. Pat. No. 6,815,892 discloses a molybdenum film for lamp construction, whose total surface area is provided with a coating. The coating is composed of a metal oxide from the group consisting of titanium oxide, lanthanum oxide, tantalum oxide, zirconium oxide, yttrium oxide and hafnium oxide.